diff --git a/.github/workflows/release.yaml b/.github/workflows/release.yaml
index 7e427d119..c0835da21 100644
--- a/.github/workflows/release.yaml
+++ b/.github/workflows/release.yaml
@@ -3,7 +3,7 @@ name: Create Release
 on:
   push:
     tags:
-      - "v*" # v0.6.1 or v0.6.1.alpha.9
+      - "v*" # v1.1.10.0 or v1.1.11.beta.1
 
 permissions:
   contents: write
@@ -15,6 +15,28 @@ jobs:
     runs-on: ubuntu-24.04
 
     steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Require version on its release branch
+        id: release_branch
+        shell: bash
+        env:
+          RELEASE_TAG: ${{ github.ref_name }}
+        run: |
+          set -euo pipefail
+          branch=$(bash scripts/release-tag-hook.sh --branch-for-tag "$RELEASE_TAG")
+          git fetch --no-tags origin \
+            '+refs/heads/main:refs/remotes/origin/main' \
+            '+refs/heads/dev:refs/remotes/origin/dev'
+          commit=$(git rev-parse 'HEAD^{commit}')
+          if ! git merge-base --is-ancestor "$commit" "refs/remotes/origin/$branch"; then
+            echo "::error::$RELEASE_TAG must point to a commit on $branch. Merge the PR before tagging."
+            exit 1
+          fi
+          echo "branch=$branch" >> "$GITHUB_OUTPUT"
+
       # Find a successful Build workflow for this exact commit.
       #
       # Release intentionally reuses the artifacts from CI rather than
@@ -24,6 +46,7 @@ jobs:
         shell: bash
         env:
           GH_TOKEN: ${{ github.token }}
+          RELEASE_BRANCH: ${{ steps.release_branch.outputs.branch }}
         run: |
           set -euo pipefail
 
@@ -33,12 +56,12 @@ jobs:
             gh api \
               -H "Accept: application/vnd.github+json" \
               "/repos/${{ github.repository }}/actions/runs?head_sha=${{ github.sha }}&status=success&per_page=100" \
-              --jq '.workflow_runs[] | select(.name == "Build") | .id' \
+              --jq ".workflow_runs[] | select(.name == \"Build\" and .event == \"push\" and .head_branch == \"$RELEASE_BRANCH\") | .id" \
               | head -n 1
           )"
 
           if [[ -z "$build_run_id" ]]; then
-            echo "::error::No successful Build workflow found for commit ${{ github.sha }}."
+            echo "::error::No successful $RELEASE_BRANCH push Build found for commit ${{ github.sha }}."
             exit 1
           fi
 
diff --git a/docs/RELEASING.md b/docs/RELEASING.md
new file mode 100644
index 000000000..6e81ac448
--- /dev/null
+++ b/docs/RELEASING.md
@@ -0,0 +1,45 @@
+# Create a release
+
+This checkout has a `reference-transaction` hook installed from `scripts/release-tag-hook.sh`. It rejects creation
+or movement of `v*` tags unless the checked-out branch matches the version policy and contains the target commit. Deleting a
+mistaken tag is still allowed. This also covers GUI tools that use Git and honor its hooks.
+
+For a new clone, install it with the following command, after checking for an existing hook to preserve:
+
+```sh
+cp scripts/release-tag-hook.sh "$(git rev-parse --git-path hooks)/reference-transaction"
+chmod +x "$(git rev-parse --git-path hooks)/reference-transaction"
+```
+
+Merge the release PR into `main` or `dev` first. Check out that branch, update it from `origin`, and wait for its
+push-triggered Build workflow to succeed. Then create the tag:
+
+```sh
+bash scripts/create-release-tag.sh v1.1.10.0
+git push origin refs/tags/v1.1.10.0
+```
+
+The script refuses feature branches, detached checkouts, tracked changes, and a local branch that differs from its
+published tip. It creates an annotated tag locally and does not push it.
+
+| Version | Required branch |
+| --- | --- |
+| `vMAJOR.MINOR.RELEASE.0`, with an even RELEASE (e.g. `v1.1.10.0`) | `main` |
+| Numeric versions with a nonzero PATCH (e.g. `v1.1.10.1`, `v1.1.11.1`) | `dev` |
+| Alpha or beta versions (e.g. `v10.1.11.beta.1`) | `dev` |
+| Odd RELEASE with PATCH 0 (e.g. `v1.1.11.0`), or any other format | Rejected |
+
+The third number determines parity, independently of major and minor. The hook, creation script, and workflow use
+the same version policy. The workflow checks that the tagged commit is reachable from the required remote branch
+and has a successful push-triggered Build on that branch; a successful PR build is insufficient.
+
+Run `python3 tests/release_tags.py` to check the version policy and Git hook in an isolated repository.
+
+Tags identify commits, not branches. Direct `git tag` bypasses the creation script but is checked by the installed
+hook. GitHub tag creation bypasses local hooks. The workflow
+blocks release publication after an invalid tag is pushed; it does not prevent or delete the tag. Tags pointing to
+older workflow versions also use those older checks.
+
+For server-side control, configure a GitHub tag ruleset for `v*` with **Restrict creations**, allowing only designated
+release maintainers or automation to bypass it. Those maintainers must use the checked creation path: the ruleset
+restricts who can create a tag, rather than which branch contains its commit.
diff --git a/scripts/create-release-tag.sh b/scripts/create-release-tag.sh
new file mode 100644
index 000000000..b6c30aafa
--- /dev/null
+++ b/scripts/create-release-tag.sh
@@ -0,0 +1,31 @@
+#!/bin/bash
+# Create a release tag only at the published main or dev tip. Push it explicitly after reviewing it.
+set -euo pipefail
+
+if [[ $# != 1 || "$1" != v* ]]; then
+  echo "Usage: $0 v<version>" >&2
+  exit 1
+fi
+tag=$1
+git check-ref-format "refs/tags/$tag"
+script_dir=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)
+required_branch=$(bash "$script_dir/release-tag-hook.sh" --branch-for-tag "$tag")
+branch=$(git symbolic-ref --quiet --short HEAD) || {
+  echo "Check out main or dev before creating a release tag." >&2
+  exit 1
+}
+if [[ $branch != "$required_branch" ]]; then
+  echo "$tag requires $required_branch; current branch: $branch" >&2
+  exit 1
+fi
+if [[ -n $(git status --porcelain --untracked-files=no) ]]; then
+  echo "Commit or stash tracked changes before creating a release tag." >&2
+  exit 1
+fi
+git fetch --no-tags origin "+refs/heads/$branch:refs/remotes/origin/$branch"
+if [[ $(git rev-parse HEAD) != $(git rev-parse "refs/remotes/origin/$branch") ]]; then
+  echo "Local $branch must match origin/$branch. Publish or update the branch before tagging." >&2
+  exit 1
+fi
+git tag -a "$tag" -m "Release $tag" HEAD
+printf 'Created %s on %s. To publish: git push origin refs/tags/%s\n' "$tag" "$branch" "$tag"
diff --git a/scripts/release-tag-hook.sh b/scripts/release-tag-hook.sh
new file mode 100644
index 000000000..9b8a6508e
--- /dev/null
+++ b/scripts/release-tag-hook.sh
@@ -0,0 +1,51 @@
+#!/bin/bash
+# Git reference-transaction hook and shared release-version policy.
+set -euo pipefail
+
+ReleaseBranch()
+{
+  local tag=$1 release patch
+  if [[ $tag =~ ^v[0-9]+\.[0-9]+\.([0-9]+)\.([0-9]+)$ ]]; then
+    release=${BASH_REMATCH[1]}
+    patch=${BASH_REMATCH[2]}
+    # Inspect decimal digits without shell integer overflow or leading-zero octal interpretation.
+    if [[ $patch =~ ^0+$ ]]; then
+      if [[ $release =~ [02468]$ ]]; then
+        echo main
+        return
+      fi
+      echo "Release tag rejected: odd releases cannot use patch 0; use an alpha/beta tag or a nonzero patch." >&2
+      return 1
+    fi
+    echo dev
+  elif [[ $tag =~ ^v[0-9]+\.[0-9]+\.[0-9]+\.(alpha|beta)\.[0-9]+$ ]]; then
+    echo dev
+  else
+    echo "Release tag rejected: expected vMAJOR.MINOR.RELEASE.PATCH or vMAJOR.MINOR.RELEASE.alpha/beta.NUMBER." >&2
+    return 1
+  fi
+}
+
+if [[ ${1:-} == --branch-for-tag ]]; then
+  [[ $# == 2 ]] || exit 1
+  ReleaseBranch "$2"
+  exit
+fi
+[[ ${1:-} == prepared ]] || exit 0
+
+while read -r old new ref; do
+  case "$ref" in refs/tags/v*) ;; *) continue ;; esac
+  # Deleting a mistaken tag must remain possible.
+  [[ $new =~ ^0+$ ]] && continue
+  required_branch=$(ReleaseBranch "${ref#refs/tags/}") || exit 1
+  branch=$(git symbolic-ref --quiet --short HEAD) || branch='detached HEAD'
+  if [[ $branch != "$required_branch" ]]; then
+    echo "Release tag rejected: ${ref#refs/tags/} requires $required_branch (currently $branch)." >&2
+    exit 1
+  fi
+  commit=$(git rev-parse --verify "$new^{commit}") || exit 1
+  if ! git merge-base --is-ancestor "$commit" "refs/heads/$branch"; then
+    echo "Release tag rejected: its commit is not on $branch. Merge the PR before tagging." >&2
+    exit 1
+  fi
+done
diff --git a/tests/release_tags.py b/tests/release_tags.py
new file mode 100644
index 000000000..8a80d7720
--- /dev/null
+++ b/tests/release_tags.py
@@ -0,0 +1,67 @@
+"""Exercise release version rules and the installed hook without changing this checkout."""
+
+from pathlib import Path
+import shutil
+import subprocess
+import tempfile
+
+
+HOOK = Path(__file__).resolve().parents[1] / "scripts/release-tag-hook.sh"
+for tag, expected in {
+    "v1.1.10.0": "main",
+    "v10.1.12.0": "main",
+    "v1.1.10.1": "dev",
+    "v1.1.11.1": "dev",
+    "v10.1.11.beta.1": "dev",
+    "v1.1.10.alpha.0": "dev",
+    "v1.1.11.0": None,
+    "v1.1.11.00": None,
+    "v1.1.10": None,
+    "v1.1.10.rc.1": None,
+    "v1.1.10.0-extra": None,
+}.items():
+    result = subprocess.run(
+        ["bash", str(HOOK), "--branch-for-tag", tag], capture_output=True, text=True
+    )
+    assert (result.returncode == 0) == (expected is not None), (tag, result.stderr)
+    if expected:
+        assert result.stdout.strip() == expected, tag
+
+with tempfile.TemporaryDirectory(prefix="stfc-release-tags-") as directory:
+    def git(*args, ok=True):
+        result = subprocess.run(
+            ["git", "-C", directory, *args], capture_output=True, text=True
+        )
+        assert (result.returncode == 0) == ok, (args, result.stderr)
+        return result.stdout.strip()
+
+    git("init", "-b", "main")
+    git("config", "user.name", "Release tests")
+    git("config", "user.email", "test@example.invalid")
+    git("commit", "--allow-empty", "-m", "Base")
+    installed = Path(directory) / ".git/hooks/reference-transaction"
+    shutil.copyfile(HOOK, installed)
+    installed.chmod(0o755)
+    git("tag", "v1.1.10.0")
+    git("tag", "-a", "v1.1.12.0", "-m", "Stable")
+    git("tag", "v1.1.10.1", ok=False)
+    git("tag", "v1.1.11.0", ok=False)
+    git("tag", "v10.1.11.beta.1", ok=False)
+    git("switch", "-c", "dev")
+    git("tag", "-a", "v10.1.11.beta.1", "-m", "Beta")
+    git("tag", "v1.1.10.1")
+    git("tag", "v1.1.14.0", ok=False)
+    git("tag", "v1.1.11.0", ok=False)
+    git("switch", "-c", "feature/test")
+    git("commit", "--allow-empty", "-m", "PR only")
+    feature = git("rev-parse", "HEAD")
+    git("tag", "v1.1.16.0", ok=False)
+    git("tag", "v1.1.11.beta.2", ok=False)
+    git("tag", "-d", "v1.1.10.0")
+    git("tag", "internal-test")
+    git("switch", "main")
+    git("tag", "v1.1.16.0", feature, ok=False)
+    git("switch", "--detach")
+    git("tag", "v1.1.16.0", ok=False)
+
+print("Release policy and Git hook checks passed")